The invention is in the field of digital echo suppressors. The echo suppressor which is the subject of this invention performs a function presently accomplished by echo suppressors manufactured by numerous telephone communications component production companies. Typical echo suppressors presently available are the Western Electric 3A and 4A, the Cogenel F3 and F4, the Lenkert 931C, the B.P.O. 7A, the Siemens 542024-A45, the WESCOM 622, and numerous other both good and bad. To the knowledge of the inventors, none of the echo suppressors manufactured today incorporates an extensive digital design or a break-in detector and the speech detector of the types incorporated in the present invention.
The present invention will provide an echo suppressor with better long term performance than that exhibited by machines of the present design. This is due to the avoidance of analog threshold adjustments which require frequent maintenance. As a consequence of this, the present invention will operate accurately for long periods of time without the necessity for adjustment. Recent studies conducted by the AT&T Company using an echo suppressor test set which permits on-line testing of echo suppressors have shown more than 50% of the echo suppressors installed are out of tolerance due to the fact that they have drifted in some manner. If these echo suppressors incorporated the concept proposed by the inventors the percent of echo suppressors performing out of tolerance would be significantly reduced.